布拉格光纖光柵特性量測技術

Abstract

在本論文中,我們使用直接側向繞射與干涉方法來量測光纖光柵的結構參數，如折射率調變變化與光柵週期之變化。在量測折射率調變的方面我們可以達到1*10-6的準確度，而在量測光柵週期方面則可達到0.01nm的準確度，整個量測的空間解析度是80μm。所量測到的折射率調變跟光柵週期變化與製作光柵時的參數與光罩規格相符，而使用轉換矩陣法跟所量得的結構參數所模擬出來的相對應光柵頻譜特性與光譜儀所量得的相吻合，同時使用間接離散剝皮法所反推出的光柵折射率調變也與直接側向繞射所量得的光柵折射率調變相同。

In this thesis we measure the structure parameters, (ac index modulation profile and variation of the grating period) of fiber Bragg grating (FBG) devices by the direct side diffraction interference method. We demonstrate the accuracy of 1*10-6 for the measurement of ac index modulation and 0.01nm for the measurement of the grating period variation with a spatial resolution of 80μm. The measured ac index profile and variation of the grating period are consistent with the intensity distribution of the UV writing laser and the chirp rate of the phase mask used in the experiment. The reflection and transmission spectra simulated by the transfer matrix method with the measured ac index and grating period are consistent with those measured by the optical spectrum analyzer. The ac index profile reconstructed from indirect “discrete Layer-Peeling method” is also consistent with that measured by the side diffraction interference method.